Electric control system.



H. A. STEEN.

ELECTRIC CONTROL SYSTEM.

APPLICATION nun NOV. 2, 1910.

Patented June 16, 1914.

2 SHEBTSSHEET 1.

H. A. STE-EN. ELECTRIC CONTROL SYSTEM. APPLIOATION FILED NOV. 2, 1910.

1,100,407, Patented June 16, 1914.

2 SHEETSSHEET 2.

- imiTED STATES PATENT orFioE.

HALFDAN STEEN, OF MILWAUKEE, WISCONSIN, ASSIGIN'OR, BY MESNE ASSIGN- MENTS, TO ALLIS-CHALMERS MANUFACTURING COMPANY, A CORPORATION OF ELECTRIC CONTROL SYSTEM.

Specification of Letters Patent. Patented Jun 1 14,

Application filed November 2, 1910. Serial No. 590,294.

To all whom it may concern:

Be it known that I, HALFDAN A. STEEN, a subject of the King of Norway, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain safety devices have been proposed for stop ping the current-increasing movement of the control apparatus when the current rises too high. These devices have been of great ing motors specifically, this is done by aucontrolling service, but they are not always adequate; for under some conditions,'as because of an increase in the mechanical load on a motor, the current may be increased without change in the control apparatus. I

t It is the object of my present invention to furnish adequate protection for translating devices, and particularly for electric motors, under all circumstances. Considertomaticallv causing curre nt-decreasingop-. eration of the controlling apparatus when the motor current exceeds a predetermined value, current-increasing movement of the apparatus preferably being sto ped at a. lower predetermined value of sue current. This current-decreasing o oration may be gradual or sudden, as esired; and may be obtained by biasing the controllin mechanism to minimum current position, and connecting it to the operating mechanism, whether operated by hand or by ower, by a clutch which is opened when t e motor current reaches the higher predetermined value. The clutch may be of any suitable kind, but is preferably of the electromagnetic type, its energizing circuit.

\ being taken off from the main motor circuit on the motor side-ofthemain motor switch. With this arrangement the opening of the main motor switch causes the automatic return of the controlling device to minimum current position. The main motor switch, which maybe a reversing switch if desired, is preferably arranged to open auto,

matically if the motor current exceeds a still higher predetermined value. In some cases it may be desirable to provide for both a gradual and a sudden current-decreasing movement of the controlling apparatus, the iiormer being obtained automatically at a somewhat lower predetermined value of motor current than is the latter. This double provision for current-decreasing movement is especially applicable to those cases where the controlling apparatus is poweroperated, in which case four steps of protection, at successively higher values of the motor. current, may be obtained; first, a stopping of the currentdncreasing movement of the controller, as by shutting off the power for the controller-operating means; second, a gradual current-decreasing movement of the controller, as by supplying power to the controller-operating means to produce a reverse movement thereof; third, a sudden current-decreasing movement of the controller, as by deenergizing an electromagnetic clutch between the controller" and its operating means; and fourth, an automatic disconnection of the motor from the supply circuit, as by the opening of the mam motor switch.

My invention is applicable to control systems of all classes, but by way of illustration I have shown it as applied to the control of wound rotor induction motors. The controller proper, in the case illustrated, is

a water rheostat, though obviously any desired form of controller may be used.

The various novel features of my invention. will appear from the description and.

drawings, and will be particularly pointed out in the claims.

Figure 1 vis a diagram showing my invention as applied to a manually o 'e'r'ated control system; and Fig. 2 is a simi ar diagram showing my invention as applied to a poweroperated control system.

The motor 10 is the motor to be controlled. It is shown as a three phase induction motor of the wound rotor type. Theprimary of this motor may be connected to the mains 11 by a reversing switch 12 which is biased to 0 en position but may 0 osed position be movedto either by a handle 13. When in either closed position, the switch 12 islocked in such position by means of a latch 14,

anism by a suitable electromagnetic clutch 19. The energizing windings of this clutch 19 are supplied from a potential transformer 20 connected across the motor leads on the motor side of the switch 12, so that upon the opening of the switch 12 or if the voltage impressed on the motor falls below a predetermined value the clutch 19 is deenergized to allow the weight 17 to return the rheostat to maximum resistance position. In the circuit of the clutch 19 is a normally closed switch 21, which may be opened by a solenoid 22 responsive to a motor current of a predetermined value, preferably somewhat less than that required for the operation of the solenoid 15.

The operating mechanism for the rheostat 16 may be operated either by hand or by power. In the arrangement shown in Fig. 1 it is operated by'a hand wheel 23 driving one part of the clutch 19 through suitable mechanism, such as a worm gear 24. On the shaft of the hand wheel 23 is a ratchet wheel 25, with which a latch 26 may be moved into engagement by a solenoid 27 to stop the forward or current-increasin movement of the hand wheel 23. The late 26 and the teeth of the wheel 25 are preferably so shaped that while their engagement prevents forward movement of the hand wheel 23 it does not prevent backward or current-decreasing movement thereof. The solenoid 27 may be supplied from the transformer 20, and its circuit is controlled by a normally open switch 28, which may be closed by a solenoid 29 responsive to a motor current somewhat less than that which actuates the solenoid 22.

The operation of the system shown in Fig. 1 is as follows: The switch 12 is closed to the proper position to obtain the desired direction of rotation of the motor 10. At this time the rheostat is necessarily in maximum resistance position, because until the closing of the switch 12 the clutch 19 has been deenergized and the weight 17 has maintained the rheostat in such position. The windings of the clutch 19, as well as those of the motor 10, being energized upon the closing of the switch 12, the hand wheel 23 may be moved to decrease the resistance of the rheostat 16. In the arrangement shown this done by immersing the plates of the rheostat 16 more deeply into the liquid thereof. Should the 2 hand wheel be moved forward too rapidly,

thus raising the motor current beyond a predetermined value, the solenoid 29 closes the switch .28, whereupon the solenoid 27 moves the latch 26 into engagement with one of the teeth of the wheel 25 to stopfurther forward movement of the hand wheel 23 and the rheostat; backward movement thereof is permitted, however. If the motor speeds up' sufiiciently to reduce the motor current below such predetermined value, the solenoid 29 allows the switch 28 to fall to deenergize the solenoid 27 and release the latch 26, whereupon the forward movement of the rheostat may be continued. However, if the motor current is increased instead of being decreased, as because of an increased mechanical load on the motor and a consequent slowing down instead of a speeding up of the motor, and exceeds a big er predetermined value, the solenoid 22 is energized sufficiently to 0 en the switch 21 to deenergize the clutc 19, whereupon the weight 17 immediately returns the rheostat to maximum resistance position. This should at once reduce the motor current below the value for which the solenoid 29 is set, for which reason the o ening of the switch 21 may also 0 en the circuit of the solenoid 27, as shown; owever, it may sometimes be desirable to have the circuit of the solenoid 27 independent of the switch 21. If the return of the rheostat-16 to maximum resistance position does not reduce the motor current v as it should, as perhaps because of the short circuit in the motor windings, and the motor current exceeds a third and still hi her predetermined value, the solenoid 15 releases the latch 14 and allows the switch 12 to open automatically, thus disconnecting the motor entirely from the supply circuit. With the arrangement shown in Fig. 1, three steps of protection are thus provided.

In the arrangement shown in Fig. 2 the rheostat is actuated by power-operated mechanism. This power-operated mechanism in this case consists of an electric motor 30, here shown as of the squirrel cage type; This motor is also preferably supplied from the transformer 20, so that the motor can only be energized when the switch 12 is closed. The circuit of the motor 30 is normally closed through the switches 31 and 32 in series, so that when the switch 12 is closed the motor 30 will operate in one direction or the other, depending upon which way the switch 12 is closed.-

operation in either direction produces a re sistance-diminishing movement of the rheostat 16 from maximum resistance position. Unless the motor current exceeds a predetermined value, this movement continues until the cam 33 on therheostat shaft 18 strikes the roller 34 and operates it and the rod sition, the opening of the switch 31 then causing the motor 30 to st However, if during this resistance-diminishing move ment of the rheostat 16 the motor current exceeds a predetermined value, a solenoid 36 is energized sufficiently strongly to open the switch 32, thus stopping such resistancediminishing movement of the motor 30 and the rheostat 16. The switch 32 will remain open, maintaining the circuit of the motor 30 broken, as long as the motor current exceeds such predetermined value, but will close to cause the motor 30 to continue its resistancediminishing movement as soon as the motor currents falls below such value. If "for any reason' the motor current does not decrease after the switch 32 has been opened, but increases to a second and higher predetermined value, the solenoid 37 closes a normally open switch 38 to complete the circuits of the motor 30 for reverse rotation, whereupon the motor 30-operates the rheostat 16 to increase the resistance thereof and diminish the current taken by the motor. This current-diminishing movement of the rheostat 16 is a gradual one. If for any reason the motor current rises still higher, and exceeds a third predetermined value, the solenoid 22 opens the switch 21 to 'deenergize the clutch 19, whereu on the weight 17 moves the rheostat 16 sud enly to maximum resistance position. Since any movement of the motor 30 is useless while the clutch 19 is dener 'zed, the opening of the switch 21 also pre erabl opens the circuit of such motor. The resu ts produced by the opening of the switch-21 will reduce the mainmotor current, in all normal cases, below the predetermined value to which the solenoid 36 is responsive, but in some ahnormal cases, as when there is a short-circuit in the motorwindings, this will not occur. If it does not, and the motor current rises. beyond a fourth and still higher pre determined value, the solenoid 15 releases the latch 14 and allows the switch 12 to open to disconnect the'motor 10 from the supply circuit. This deenergizes all windings, whether solenoid, clutch, or motor windings, of the system. In the arrangement shown in Fig. 2 thereare thus four steps of protection. The switches 32, 38, and 21 are shown all s arate and all operated by separate solenoidh; but this is merely by way of illustration. In some cases, the actuating solenoids of these switches, or of some of them, and indeed the switches themselves, may be combined.

The arrangements shown, it is believed furnish adequate protection for all cases which may arise. In many cases, however, some of the protective steps may be omitted, the systems being modified accordingly in a manner sufficiently obvious.

Many modifications may be made in the precise ar meats shown and described, and in the i lowing claims I aim to cover all schemes which come within the spirit and scope of my invention.

What I claim as new is:

1. In combination, a translating device, a controller therefor, means for starting a current-increasing movement of said controller, means for stopping the current-increasing movement of such controller when the current taken by the translating device exceeds a predetermined value, and means for causing a current-decreasing movement of the controller when the current taken by the translating device exceeds a higher predetermined value. I a

2. In combination, a translating device, a controller therefor, means for moving said controller gradually in a direction to increase the current in the translating device, means for stopping such movement when such current exceeds a predeterminedvalue, and means for causing a sudden movement of the controller in the reverse direction when such current exceeds a higher predetermined value.

3. In combination, a translating device,

a controller therefor, means for starting a current-increasing movement of said controller, means for causing a stop ping of the current-increasing movement or-such controller when the current taken by the translating device exceeds a predetermined value, means for causing a reverse movement of the controller when such current exceeds a higher predetermined value, and means for opening the circuit of the translating device when the current taken thereby exceeds a still higher predetermined value.

4. In combination, a translating device, a controller therefor, means for moving the controller from an initial position to increase the current taken by the translating device, means for stoppin such movement of the controller when suc current exceeds a predetermined value, means for caus ng the controller to return suddenly to its 1mtial position when such current exceeds a higher predetermined value, and means for opening the circuit of the translating device when such current exceeds a still highe predetermined value. I

5. In combination, a translating dev ce, a controller therefor, said controller being biased to aniniti-al position, operatin mechanism for the controller, a clutch or conmeeting the operating mechanism to the corn troller, means for stop ing the movement of the controller away om its initial position by said operating mechanism when the current taken by the translating device exceeds a predetermined value, and means for causing the opening of said clutch when the current taken by said translating device exceeds a higher predetermined value.

6. In combination, a translating device, a controller therefor, said controller being biased to minimum current position, operating mechanism for the controller, an electromagnetic clutch for connecting said operating mechanism to said controller, means 'for causing the stoppin of the movement ofsaid controller away rom minimum current position by said operating mechanism when the current taken by the translating device exceeds a predetermined value, and means for causing the deenergization of said clutch when the current taken by the translating device exceeds a higher lpredetermined value.

7. .In combination, a translating device, a switch in the supply circuit thereof, a controller for said. translating device, means for producing a current-increasing movement of said controller when the current taken by the translating device is below a predetermined value, for causin a gradual current-decreasing movement 0 said controller when such current exceeds a predetermined value, and for causing a sudden current-decreasing movement of the controller when such current exceeds a higher predetermined value, and means for causing the opening of said switch when the current taken by the-translating device exceeds a still higher predetermined value.

8. In combination, a translating device, a controller-for said translating device, and means for producing a current-increasing movement of said controller when the current taken by the translating device is below a: predetermined value, for causing a gradual current-decreasing movement of said controller when such current exceeds a predetermined value, and forcausing a sudden mined value, means for stopping such movement when suchcurrent exceeds such predetermined value, means for causing a gradual current-decreasing movement of the controller whensuch current exceeds a higher predetermined value, means for causing a sudden current-decreasing movement of the controller when such current exceeds a still higher'predetermined value, and means for causing the opening of said switchwhen such current exceeds a fourth predetermined value.

higher predetermined value, and means for causing a sudden current-decreasing movement of the controller when such current exceeds a still higher predetermined value.

11. In combination, a motor, a starting controller therefor, "power operated means for operating said starting controller and normally operating it to increase the motor speed, means for disconnecting said ower operated means from said controller 1n response to abnormal circuit conditions with out materially affecting the operation of said motor, and means for causing a reversal ofthe direction in which said power-operated means operates said controller if the current taken by the motor exceeds a predetermined value.

12. In combination, a motor, a starting controller therefor, a pilot motor for operating said controller, said pilot motor normally operating the controller to increase the speed of the main motor, and means for reversing the pilot motor when the current taken by the main motor exceeds a predetermined value and for disconnecting said controller from said pilot motor in response to abnormal circuit conditions vvithout causing the main motor to discontinue operation.

13. In combination, a motor, a starting controller therefor, power-operated means for operating said controller, a clutch for connecting said power-operated means to said controller, and means for reversing the direction in which said power-operated means operates said controller when the current taken by the motor exceeds a predetermined value and for causing the openin of said clutch when such current excee s a higher predetermined value.

14. In combination, a motor, a starting controller therefor, power-operated means for operating said controller, a clutch through which said operating mechanism operates said controller, and means for stopping the operation of said controller by said operating mechanism when the current taken by the motor exceeds a predetermined value and for causing the opening of said clutch when the current taken by. the motor exceeds a higher predetermined value.

15. In combination, a motor, a starting controller therefor including a resistance circuit, means for operating said controller, a clutch through which the controller is operated by said means, and means independent of said resistance circuit for causing the opening of said clutch while permitting the operation ofsaid motor when the-current taken by the motor exceeds a predetermined value. I

16. In combination, a motor, a starting controller therefor, said controller being biased to minimum current position, means for moving said controller away from such position, a clutch through which said means operates said controller, and means for stopping the movement of said controller by said first mentioned means when the current taken by the motor exceeds a predetermined value and for causing the opening of said clutch when such current exceeds a higher predetermined value.

17'. In combination, a motor, a starting controller therefor, said controller being .biased to minimum current position, poweroperated means for moving said controller away from such position, a clutch through which the power-operated means operates said controller, means forreversing the direction in which said power-operated means operates the controller when the current taken by the motor exceeds a predetermined value, and means for causing the opening of said clutch when such current exceeds a higher predetermined value.

'18. In combination, a motor, a cont-roller therefor including a resistance circuit, a clutch forconnecting said controller to a source of power, and means independentof said resistance circuit for causing the opening of said clutch without materially affect-- ing the operation of said motor when the current taken by the motor exceeds a predetermined value 19. In combination, a motor, a starting controller therefor including a resistance circuit, said controller being biased to minimum current position, a clutch for connecting said controller to a source of power to move the controller away from such position, and means independent of said resist ance circuit for causing the opening of said clutch without causing said motor to discontinue operation when the current taken by'the motorexceeds a predetermined value.

-20. In combination, a motor, a starting controller therefor, said controller being biased to an initial position, a clutch for connecting said controller to a source of power to move the controller away from such position, means for stopping such movement of said controller when the current taken by the motor exceeds a predetermined value, and means for causing the opening of said clutch when such current exceeds a higher predetermined value.

21. In combination, a motor, a starting.

controller therefor, said controller being biased to an initial position, a clutch for connecting said controller to a source of power to move such controller awa from such position, and means for reversing the direction in which sald controller is operated when the current taken by the motor exceeds a predetermined value, and for causing the opening of said clutch when such current exceeds a higher predetermined value.

22. In combination, a motor, a controller therefor, power-operated means for moving said controller, a clutch through which said oit er-operated means operates said controller, means for causing the opening of said clutch when the current taken by the motor exceeds a. predetermined value, and means for causing a reversal of the direction in which said power-operated means operates the controller when such current exceeds another predetermined value.

23. In combination, a motor, a controller therefor, a clutch for connect-ing said controller to a source of power, and means for causing the opening of said clutch when the current taken by the mot-or exceeds one predetermined value and for causing a reversal of the direction in which the controller is operated when such current exceeds a different predetermined value.

24; In combination, a motor, a starting cont-roller therefor, power-operated means for operating said starting controller and normally operating it to increase the mot-or speed, means for stopping such operation of the controller by said power-operated means when the cont-roller has reached maximum speed position, and means for causing a reversal of the direction in which said poweroperated means operates said controller if the current taken by the motor exceeds a predetermined value.

5. In combination, a motor, a starting controller therefor, power-operated means for operating said controller and normally operating it in a direction to increase the motor speed, means for stopping the operation of said-controller by said power-operated means when either the controller has reached maximum speed position or the current takenv by the motor exceeds a predetermined value, and means for reversing the direction in which the power-operated means operates the controller when such current exceeds a higher predetermined value.

26. In combination, a motor, a power-operated starting controller therefor, said controller being operated normally to increase the motor speed, and controlling means forsaid controller actin to' cause a reversal of the direction in w ich said controller is operated if the current taken by the motor exceeds a predetermined value and to separate said controllerfrom the source of power the motor speed, means movable with the taken by the translatin controller for stoppin the operation of said starting controller w en it reaches maxi mum spee'dposition, separate means for causing a reversal of the direction in WhlCh said controller is operated if the cur-rent taken by the motor exceeds a predetermined value, and means responsive to a higher predetermined value of said current or stopping the operation of said controller.

28. In combination, a main motor, a reversing switch for connecting it to a supply circuit, a controller for the motor, said controller being biased to a middle position from which it is movable in either directionto increase the motor speed, a pilot motor for operating said controller, and an electromagnetic clutch for mechanically connecting said pilot motor and said controller, sald pilot motor and said clutch .both having windings connected across the main motor circuit on the motor side of the reversing switch. y 29. In combination, a translating device, a controller therefor, said controller being biased to an initial position, operating mechanism for the controller, means for connectin g the operating mechanism to the controller, means for stopping the movement of the controller away from its initial position by said operating mechanism when the current taken by the translating device exceeds a predetermined value, and means for causing said first mentioned means to become ineffective when the current taken by said translatin device exceeds a higher predetermined va ue..-

30. In combination, a translating device, a controller therefor, said controller being biased to a minimum current position, op-- erating mechanism for the controller, means for connecting said operating mechanism to said controller, means for causing the stopping of the movement of said controller away from minimum current position by said operating mechanism when the current device exceeds a predetermined value an means for causing said first mentione means to become in: effective when the current taken by the translating device exceeds a higher predetermined value.

31. In combination, a motor, a starting controller therefor, power-operated means for operating said controller, means for connectin said power-operated means to said contro ler, and means for reversingthe di rectlon 1n Wl'llCh sa1d ower-operated means operates said control er when the current taken by the motor exceeds a predetermined value and for causing said connecting means to become ineffective when said current exceeds a higher predetermined value.

for operating said controller, means through which said operating mechanism operates said controller, and means for stopping the operationof said controller by said operating mechanism when the current taken by the motor exceeds a predetermined value and for causing said second mentioned means to become ineffective when the current taken by the motor exceeds a higher predetermined value.

33. In combination, a motor, a starting controller therefor, said controller being biased to a minimum current position, power-operated means for moving said controller away from such position, means through which the power-operated means operates said controller, means for reversing the direction in which said power-operate means operates the controller when the current taken by the motor exceeds a predetermined value, and means for causing said second mentioned means for becomin ineffective when such current exceeds a higher predetermined value.

34. In combination, a motor, a starting controller therefor, said controller being biased to an initial position, means for connectingsaid controller to a source of'power to move the controller away from such position, means for stopping such movement of said controller when the current taken by the motor exceeds a predetermined value, and means for causin said first mentioned means to become ine ective when such current exceeds a higher predetermined value.

35. In combination, a translating device,

a controller therefor, said controller being.

said controller, means responsive to abnormal circuit conditions to render said oper- 1115 ating means ineffective, a clutch throu h which the, controller is operated by said means, and overload responsive means for causing the o ening of said clutch when the current ta en by the motor exceeds a 120,

predetermined value.

37. In combination, a motor, a starting controller therefor, said controller being biased to minimum current position, means for moving said controller away from such position, means responsive to abnormal circuit conditions to render said means ineffective, a clutch throu h which said means operates said .contrdller, and overload responsive means for causig the biased to minimum current position, a

clutch for connecting said controller to a source of power to move the controller away from such position, means responsive to abnormal circuit conditions to stop said controller whilethe clutch is effective, and overload responsive means for causing the opening of said clutch when the current.

taken by the motor exceeds a predetermined value. a

40. In combination, a motor, a starting controller therefor, means for, operating said controller a clutch between said controller and said operating means, and means responsive to abnormal current conditions in, the circuit of the. motor for actuating said clutch to disconnect said operating means from said controller while permitting the operation of said 'motor.

41. In combination, a motor, a starting controller therefor, a pilot motor for operating said controller and tending when the main motor is starting to operate the controller to increase thespeed ofthe main motor, and controlling means for said pilot motor responsive. to \current conditions in I Patent Ofiice.

Correctionj in Letters Patent No, 1,100,407.

Signedand sealed this 7th day of July, A. D., 1914:.

the main motor circuitvand acting to stop the pilot motor when the current in the main motor circuit exceeds a predetermined value, and to reverse the pilot motor when such current exceeds a higher predetermined value, and to disconnect the pilot motor from the controller without stopping the operation of the main motor.

42. In combination, a motor, a starting controller therefor including a resistance circuit, means for operating said controller, a clutch through which the cont-roller is egerated by said means, and means indepen ent of said resistance circuit for. rendering said operating means inactive when the current taken by the motor exceeds a predetermined value and for causing the openingof said clutch when said current exceeds a higher predetermined value.

43. In combination, a. translating device, a controller therefor, said controller being biased to initial position, operating mechanism for said controller, a clutch for connecting the operating mechanism to said controller, current responsive means for rendering said operating mechanism inactive when the current taken by said translatin device exceeds a predetermined value and or actuating said clutch todisconnect said controller from said operating mechanism when said current exceeds a higher predetermined value.

Milwaukee, Wis, Oct. 29, 1910. I

In testimony whereof I aflix my signature, in the presence of two witnesses.

Witnesses:

Gno. B. SCHLEY, CHAs. L. BYRON.

It is hereby certified that in Letters Patent No. 1,100,407, granted June 16, 1914,

ment in Electric Control Systems, an error appears in the printedspecification the word mowing; and that the said Letters Patentshould be read with this correction'therein that the same may conform to the record of the case in the 111+. HITEHE Acting Commissioner ofPatqnta. v

HALFDAN A. STEEN. g

upon the application of I-Ialfdan A. Steen, of Milwaukee, Wisconsin, for an improverequiring correction as follows: Page 6, line 128, before the word means" insert 

